Bug 1808871 connect mStreamName Mirror r=alwu

Differential Revision: https://phabricator.services.mozilla.com/D166245

dom/media/MediaDecoderStateMachine.cpp

@@ -3325,6 +3325,7 @@ void MediaDecoderStateMachine::InitializationTask(MediaDecoder* aDecoder) {
   MediaDecoderStateMachineBase::InitializationTask(aDecoder);
 
   // Connect mirrors.
+  mStreamName.Connect(aDecoder->CanonicalStreamName());
   mSinkDevice.Connect(aDecoder->CanonicalSinkDevice());
   mOutputCaptureState.Connect(aDecoder->CanonicalOutputCaptureState());
   mOutputDummyTrack.Connect(aDecoder->CanonicalOutputDummyTrack());